The proposed project is a multi-method, longitudinal investigation of the effects of formal and informal social support systems on drug-using populations in a nontreatment setting. The project establishes and evaluates the efficacy of using a community-based service model (CBS), combining case management and peer self-help strategies, to promote reduced and drug-free living among active and recovering drug users. Long term study objectives are: (1) to understand the nature and significance of social support systems currently available to active and recovering drug users in a northside and southside community setting in Chicago; (2) to establish and evaluate the efficacy of using a community-based service model in nontreatment settings to reduce illicit drug use and to limit the spread of human immunodeficiency virus (HIV) among current and recovering drug users; (3) to evaluate the effects of the CBS model on the physical health and social well-being of drug abusers who receive this intervention; and (4) to determine the indirect effects of participation in such a program on the social network of persons receiving this intervention. Using previously established research-relations, 200 active drug abusers in a northside and southside Chicago neighborhood will be recruited by indigenous outreach workers, then randomly assigned to a control (existing treatment) or CBS intervention group in their respective community setting for comparison. Subjects will be measured at intake, 3 weeks, 3 months, 6 months, 9 months, and 12 months during the first year and at 6 month intervals in years 2-4. Three sets of quantitative measures will be administered at intake and during follow-up: the Addiction Severity Index, the Symptom Check List-90-Revised, and a social support inventory. Ethnographic collected on the informal and formal social support system& available to drug users will be combined with case-record information to identify, describe, and evaluate social support systems currently available to drug users. In addition to addressing its research aims, the intervention program is expected to serve as a model for public health agencies developing health promotion and drug-treatment service capabilities.